Troubleshooting Brake Controller Installations

Even the most experienced installer will encounter it from time to time: the brake controller installation is finished, the wires have all been run, but something is going wrong. Whether your controller is showing an error message or the trailer brakes just aren't working, there are a number of troubleshooting techniques you can use to get the problem fixed and get back on the road. Using the following information and testing procedures, you should be able to pinpoint and eliminate the most common issues encountered during and after a brake controller installation.

Common Brake Control Issues

ProblemPossible IssuesTesting Procedures
Brake controller display does not show that trailer is connected.
  1. Short on brake signal wire, trailer or vehicle side.
  2. Corrosion in trailer and/or vehicle plug.
  3. Short on brake magnets on trailer.
  4. Malfunctioning brake magnet(s).
Brake controller loses connection to battery ground.
  1. Ground wire was not connected to negative battery terminal, ground area does not have solid connection to ground.
  2. Adapter wiring does not match OEM connector on vehicle.
  3. Ground connection to negative battery terminal is loose.
  4. Ground wire has been damaged and exposed wiring is touching a metal area.
Brakes are applying too aggressively for the brake controller settings.
  1. Brake assemblies are not properly adjusted.
  2. Boost/Gain on brake controller is set too high for trailer size.
  • Adjust brakes properly (see video).
  • See brake control owner's manual for proper boost/gain settings for trailer size.
Trailer brakes only work with manual control, not with brake pedal. (Be sure to test for proper brake controller function with unloaded trailer in a safe area where you can reach low road speed before you determine that the brake controller is not working)
  1. Incorrect stoplight wire connection.
  2. Adapter wiring layout does not match OEM connector on vehicle.
Brake controller detects an overload condition during use.
  1. Trailer has too many brakes for brake controller to handle.
  2. Corrosion in trailer and/or vehicle plug.
  3. Brake signal wire on trailer is damaged, exposed wiring is touching metal area or another circuit.
  4. Malfunctioning brake magnet(s).
Display is erratic while braking.
  1. Short to battery on 12V wire connection.
  2. Short on brake signal wire, trailer or vehicle side
  3. Corrosion in trailer and/or vehicle plug.
  4. 12V wire was not connected to vehicle battery, 12V source used is not constant.
Brake controller detects a short on the brake wire while vehicle is idling.
  1. Corrosion in trailer and/or vehicle plug.
  2. Brake signal wire on trailer or vehicle is damaged, exposed wiring is touching metal area.
Trailer brakes engage when it is plugged into the vehicle.
  1. Incorrect stoplight wire connection.
  2. Corrosion in trailer and/or vehicle plug.
  3. Adapter wiring does not match OEM connector on vehicle.
Brake controller does not turn on.
  1. Connection to battery is not complete.
  2. Vehicle is missing a fuse or relay required to power 12V power circuit.
  3. Adapter wiring layout does not match OEM connector on vehicle.
  • Method 1
  • Check fuse block for missing fuse/relay. See vehicle-specific FAQ if available, or check owner's manual.

Basic Testing Procedures

Method 1: Verifying Correct Wire Connections (Hard Wire Installs)

Testing the Stoplight WireBrake Control Wire Colors

Wiring Adapter vs. OEM Connector

Method 1: Verifying Correct Wire Connections (Plug-in Installs)

Method 2: Testing for the Brake Signal

Testing the Blue Wire

Method 3: Looking for a Short or Ground Issue

Damaged Wiring

Method 4: Inspecting the Brake Assemblies

Brake Magnets

For more information, see:

Updated by: Raymond P.

Last updated: 7/5/18

Questions and Comments about this Article


Recently got an RV and had a 7-Way replaced on our tow vehicle. Got a Curt Echo as the brake controller. Towed the first few days fine but now is showing 'electrical overload' almost always. Any ideas? 94580

Reply from Chris R.

I linked an answer page below that does a nice job of breaking down the troubleshooting process for this particular issue on the Echo. If it does not help please let us know. 70035


I drive a 2014 Dodge Ram 1500 series I just installed a trailer brake controller (Tekonsha). My control panel on my truck is now stating I have a brake light out but when I check it it’s not out. Any suggestions 86330

Reply from Chris R.

Does the new brake controller seem to be working fine? I wonder if there's just some debris/corrosion inside the pins of the 7-Way that needs to be cleaned out. I would check that first and then go from there. Let me know what you find. 68276

Bob B.

I just installed an oem integrated brake module and switch in my 2014 ram 1500 and had the dealer update the computer to recognize it. Two issues I cannot figure out 1) the trailer disconnect light is on all the time when there isn’t a trailer and everything I read states it shouldn’t stay on 2) on the switch, the button to decrease the gain as well as the manual braking works; however the button to increase the gain does not work at all. For issue 1) I have no idea how to troubleshoot at this point, for issue 2) how can I tell if this is the module or the switch? I’ve cleaned and tested all connections and same issues. 84376

Reply from Chris R.

Since we're dealing with OEM components I really can't offer too much in the way of troubleshooting tips. If the gain button isn't working this points more to an internal issue on the controller itself, not really anything with the wiring. Have you contacted the dealer that installed all of this? I would think they would be on the hook if it's not working correctly. 67622

Monti R.

I just installed a Tekonsha pioneer brake controller In my ‘p3 Ford F-150. It does not light up at all. Does the trailer also have to be connected to see any reaction? Are there any fuses or relays that I should check out? What else could it be? 81472

Reply from Chris R.

If it's not lighting up at all then it's not getting power. You don't need to be hooked up to a trailer for it to light up but you may need to start the truck. If the ignition is on and you still aren't getting anything there's likely a blown fuse under the hood. Check your owner's manual for the fuse location that's linked to the brake controller circuit and replace it. If this doesn't help let me know. 66918

Justin T.

hello, I have a 2014, RAM, 3500, 6.4 HEMI CAB CHASSIS-DUALLY, DUMP. Fully loaded, traction control,has tow haul mode, selectable shift IN D- 1-5,6 spd auto?. It was put together by dealer, or truck body installer? From hat I know.. We started too notice problems, like ABS, TRACTION CONTROL, 4WD NOT AVAILABLE, POPPING UP, on the display screen..w. these errors, you cant get it into 4wd, and you can feel the ABS, WORKING ODDLY/NOT WORKING, Because front tires would lockup on gravel.. ANYWAY, I figured out that, The problem had something too do with everytime we plugged in our 6k lb bandit chipper, and also with a smaller tandem axle trailer.. Funny thing is, the trailer brakes work fine, signals, lights etc.. And if you unhooked the trailer plug, shut truck on-off, and drove the errors would go away, and truck would be all good. Now, It DOES NOT HAVE, a factory trailer brake, OEM TRAILER BRAKE-IN Dash control, NOR, Does it have anything for trailer brake control in the MENU/SETTINGS//DISPLAY.. they seem to have installed a basic, aftermarket Trailer brake controller, and a Plug/jumper harness plugged into the truck.. The problems wouldn't SHOW with other trucks and SAME trailers, I towed and tested the chipper and trailer with 2 other rams, A 2003, & 2008, but no problems.. So im starting too think, theres something not setup, or flashed, in the ecm/tcm etc, since theres no settings for it in the menu, but would it matter? since its a aftermarket unit? ALL Trailers,tows, are electric magnetic typicall 5k lb brake systems..BUT... possible the trailer brakes, brake lights are back-feeding into the tcs/abs system etc of the truck?, causing the errors,?? Possibly the truck need to be flashed/setup by dealer for the trailer brake controller? Or is there a certain, special aftermarket controller that works with the 14' RAM truck oem system? just wondering if I narrowed this down in the rite direction?.. I tested the 7 pins many times on everything and says all good.. (I can Read/use A - VOHM meter fairly well- basic electrical schooling and auto diagnostics) and all checked out.. Besides, the other trucks have no problems towing same stuff...BUT, they don't have the TCS/ABS, AND ELECTRICAL 4WD, "FULLY LOADED STYLE" Like the 2014 RAM... That's my theses so far. ANY HELP ON THE ISSUE W/ THIS 2014' RAM AND TBC WOULD BE GREAT!! -THANKS- PS. The dealer went over it many times, never found a single problem, BUT, the trailer was NOT hooked up, so they wouldn't have seen the errors, problems Ive been having.. 77716

Reply from Chris R.

Since it sounds like you have an aftermarket brake controller on your truck, you wouldn't have any of its settings show up on the OEM dash or panel in the cab. Any settings would be adjusted on the controller itself. Since the Ram wasn't equipped with the factory brake controller, it shouldn't need to be flashed to properly recognize the aftermarket unit. It sounds like the red wire from the controller might be attached to the wrong wire on the truck - make sure it's connected to a wire behind the brake pedal that ONLY receives power when the pedal is depressed (and no power with any other function). Hooking up to the wrong wire can definitely cause issues with the truck. Let me know what you find and we can keep troubleshooting if needed. 63096

Chris J.

I have had a Tekonsha Prodigy P3 controller installed in my 2012 Toyota Highlander. I have never had an issue until I last connected my camp earlier this year. The display was dark on the controller. All of the lights to the trailer functioned as normal but no power. Do the circuit breakers sometimes go bad on these? I installed the wiring as directed with the install kit I purchased from you and had no issues. I need to get in there and probe the wires but thought if it could be the circuit breaker that might be fastest and easiest fix. I don't seem to have power at the controller or at the 7 pin connector. Where else should i look? Should i try a new set of breakers first? 77491

Reply from Chris R.

It sounds like the Prodigy P3 isn't getting enough power from the truck. I would definitely check the circuit breaker and make sure you've still got a good, secure connection to the battery under the hood. You might also just try resetting the P3 itself by simply unplugging completely, letting it sit for a bit, and plugging it back in. Let me know what you find and we'll go from there. 63095

Reply from Chris J.

@ChrisR I tried to reset it and even borrowed another one to see if that was the issue. I am now sure it is a power issue sk I guess I need to get in there and track it down. Thanks for the reply! 63194

Reply from Chris R.

@ChrisJ Thanks for the info. If the same issue happened on a different controller, it's definitely the 12V power circuit going into the unit. Let me know if you have issues tracking the problem down! 63381

Steve C.

I have a huskie quest in my 2010 Toyota Tundra and pull a 32ft Coleman T.T. When we bought the trailer 3 years ago, they installed the brake and it seemed to work. I just took a trip to Oregon from California and it just didn't seem right. The display basically just stayed at 0 when I would brake. If I push the brake pedal fast, it will shoot up to a two digit number (that I can't really see) and then instantly display 0. If I manually squeeze the button, I can feel the trailer lock up and see it display 99. Shouldn't I see a number displayed when I brake, Especially on the freeway at higher speeds? I also noticed a lot of brake dust coming from my two front truck tires (haven't noticed that before while towing). Also, what number range should it be set to while in the valley on freeways? What about in the mountains? Thank you all in advance. 76856

Reply from Chris R.

It seems like it's somehow lost a good connection with the brake light switch in your truck. You mentioned buying it a few years ago - has it worked fine up until the most recent trip? Check to make sure that the red wire coming from the Quest still has a good connection and inspect the 7-Way connector at the bumper for any debris/corrosion that might be built up inside the pins, cleaning out as needed. Let me know what you find and we'll go from there. 62646

Reply from Steve C.

@ChrisR Thank you SOO much. I will get right on it. Also, yes It seems it was working differently a while back 62659

Reply from Chris R.

@SteveC Great - don't hesitate to reach back out if this doesn't work to resolve the issue. 62841

Devon S.

I recently had the tekonsha primus installed on my f650 by a professional to handle my triple axle works good however without the trailer connected just driving down the road with the truck if I engage the trailer brake controller and hold it down it causes the truck to lose power and then it starts downshifting. Could it be installed wrong? 76393

Reply from Chris R.

That's an interesting issue and it definitely points to something being hooked up incorrectly, most likely with the red wire on the Primus controller. It should be connected to a wire that ONLY sees power when pressing down on the brake pedal (and no power with any other function). You might take the trailer back up to the shop you had the controller installed so they can inspect everything - it really shouldn't be drawing any power away from your F-650. 62353

Reply from Paul G.

@ChrisR When you manually apply the brake controller it not only sends voltage to the trailer brakes but to the brake light circuit as well. However the truck sees voltage in this circuit and because yours is automatic it commands the downshifts. 66647

Jeff R.

With my trailer jacked up and spinning wheels by hand trailer brake works only with manual switch on controller. With circuit tester, red wire, on back of brake controller is lighting up when brake pedal is pressed. 7 pole plug lights up on electric trailer brake tab with circuit tester when brake is applied by foot although not as bright as when manual switch is applied-is that normal? Not sure where my problem is. 73743

Reply from Chris R.

If you have a proportional brake controller, what you're describing is actually completely normal. A proportional controller sends back power based on deceleration - so if you're testing it by pressing on the brake pedal with the trailer sitting still, it's going to send back very little power (if any at all). The manual override switch will always send back full power no matter what. 60083

Brandon B.

My trailer brakes were working great on a 5 hour trip. Then on the way home, they suddenly stopped working. I have the POD pro series 80500. The light makes a click and barely gets a hint of yellow to it even when the power is turned all the way up manual override or with the pedal. Could the unit be bad after just about 7 hours of use? 73667

Reply from Chris R.

It would certainly be unusual for the PowerTrac Controller to go bad after just a single trip (one-way). Was the unit installed using a Plug-In Adapter or was it hardwired in? It sounds like it's suddenly not getting enough power in - make sure you've still got a good connection with the battery if it was hardwired. If you used a Plug-In Adapter, make sure those plugs are still fully seated and connected. Let me know what you find and we'll go from there. 60082

Reply from Brandon B.

I used the plug in adapter and the connections are good. Had a friend hook his truck up with another brake controller (unknown brand) and his light flashed green. So it seems that the problem is in the trailer and not the truck or controller. The ground on the trailer seemed "iffy" so I re-attached it to the frame. Guess I will redo the plug and check out the brakes themselves to see if any wires came loose? 60116

Reply from Chris R.

Along with the main trailer ground, also check the individual grounds coming from each brake assembly. Inspect the trailer side 7-Way too for any debris or corrosion that might be built up inside the pins, cleaning out as needed. 60186


Does the black wire have to be connected to battery? I would like to wire to ignition so the small led light does not cause the battery to die? 71400

Reply from Chris R.

The brake controller needs the constant and reliable power that can only be provided by wiring it directly to the battery. That pesky LED light makes a lot of people nervous, but I can assure you that it doesn't draw enough power to cause any issues. It would take months and months (and months) of the vehicle sitting idle for it drain the battery. 58302


trailer brakes wont work through controller. but will work when you pull trailer disconnect. hook to different truck and brakes lock up immediately. is there supposed to be power on the trialer stop wire when brakes are applied 71004

Reply from Chris R.

There definitely should be power on the brake output wire when applying the brakes in the tow vehicle. If you're using a proportional brake controller though you will only get power if you're actually moving (not just when testing in the driveway). Have you checked to see if the brakes lock up when applying the manual override on the controller? 57972

Dave M.

With no trailer connected i have 4.4 volts at trailer brake pin on truck side. is this right? 70582

Reply from Chris R.

A trailer brake controller will constantly send small pulses of voltage back to the 7-Way - with or without a trailer attached. It's basically the controller's way of playing "Marco Polo" to detect if/when a trailer is connected. This is completely normal and while 4.4 volts might be a LITTLE more than usual, as long as it's not causing any problems when towing (your brakes aren't engaging when they shouldn't be) it's not something you need to worry about. 57592

Brent M.

I tow a triple axle hydraulic dump bed with a Chevy 2500 HD diesel. Factory trailer tow package and controller. It’s always towed fine, this first time it’s happened. No I haven’t pulled it again, but want to soon. As soon as I do I’ll let you know. It’s been a muddy as heck in KS, should dry up in a few days. Thanks 70424

Reply from Chris R.

Sounds good. That exposed portion of wire you found could have just been causing a short, so hopefully it's all fixed up now. Just let me know if you run into any issues again! 57489

Brent M.

Trailer brakes intermittently engage while driving. Seems perhaps the bumps in the road cause this, maybe not. One thing for sure they lock up and disengage causing truck to downshift immediately and all gauges to . Checked wiring and found bare spot, I insulated the conductor and made sure all grounds had good metal connections. What do you think though ? 70395

Reply from Chris R.

Have you towed again since locating and repairing the bare spot you mentioned on the wiring? What model brake controller are you using (or is it a factory unit)? Depending on the model, and if it's a proportional unit, I wonder if the sensitivity needs to be decreased a bit. It might just be sending back power every time you decelerate even a little. Let me know what you find and we can go from there! 57474


Why does my breaks lock up when I turn key on my controler pWorks perfect until I turn on my key then it locks up breaks on trailer. 64975

Reply from Jacob H.

If your brakes are locking up as soon as you turn the key in the on position, then it means that you have constant 12V power going to the break output from an ignition source. I would check your wiring and rewire it if this is the case. The best way to test the wires is to use a circuit tester # 40376 to make sure you are getting the right signals going to the correct wires on the back of the brake controller. Another potential problem could be the pins may have corrosion on the 7-pole plug. What can happen is the pins will corrode eventually causing them to cross. In your case you would have the 12V pin crossing with the break signal pin. If this is the case cleaning the pins off should solve your issue. 55388



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